1. Field of the Invention
The present invention relates to an ignition device that mainly uses a plasma discharge by alternative current (AC) power.
2. Description of the Related Art
In recent years, the problem of environmental conservation and fossil fuel depletion has been raised and it becomes an urgent need to deal with these also in the automotive industry. As an example dealing with this, there is a method of dramatically improving the amount of fuel consumption by reducing a pumping loss by the use of exhaust gas recirculation (EGR).
However, combusted gas, which is exhaust air, is incombustible and has a larger thermal capacity than that of air; and accordingly, if a large amount of combusted gas is sucked again by the EGR, a problem exists in that ignition quality and combustion quality deteriorate.
As one of solutions of this problem, there has been proposed an ignition device shown in, for example, Patent Document 1, in which a corona discharge is used to ignite at many points and in a wide range, whereby a more stable flame kernel can be formed and combustion quality can be stabilized.
The ignition device disclosed in Patent Document 1 is used, whereby the more stable flame kernel can be formed as compared to a conventional ignition coil and stable combustion can be obtained even when, for example, the aforementioned amount of EGR gas is supplied. Therefore, since larger EGR can be supplied and a pumping loss can be reduced as compared to the conventional ignition device by using, for example, the ignition device disclosed in Patent Document 1, there can be obtained an internal combustion engine that can dramatically improve the amount of fuel consumption.
Patent Document 1: Japanese Translation of PCT International Application No. 2014-513760
In the ignition device disclosed in Patent Document 1, an energy supply section (high voltage supply device) and a driving circuit are arranged as different packages and these can be connected by wiring.
In the ignition device disclosed in Patent Document 1, as a voltage supplied from the energy supply section becomes higher, a step-up rate from the driving circuit to the ignition coil can be suppressed lower and a current to be supplied to the ignition coil can be suppressed smaller; and therefore, operation can be efficiently performed.
However, when the voltage of the energy supply section connected to the driving circuit by wiring is raised, an electric shock and/or a leak may be caused by coating deterioration of the wiring, a fitting defect of a connector, a disconnection, and the like.